His Sister's Best Friend
by dayuuuumgirl
Summary: For all intents and purposes, she was only another girl. Looks: average. Shoe size: average. Height: below average. Throughout elementary school, middle school, and high school, she was just his younger sister's best friend. Until she wasn't. T for slight language.


**So I know I should be working on The Kissing Dilemma, but this popped into my head. And I had to write it because I only write when I'm inspired :D**

**Characters are all human **

**Elementary School**

Dirt and blood covered his knees. Again.

Jace trudged up the steps to his house, head down and angry. So what if he kissed Celine in the tunnel on the playground? This was a free country, and he had his rights. He could kiss anyone he wanted, any time, any place. It wasn't like he was raping her or anything. Besides, third grade wasn't too young for kissing, was it?

Shouting in frustration, he kicked a pot of orchids outside the door and sprung back, howling. But this pain was far less intense than what he had experienced out on the playground, where Celine's older brothers had dragged him away by his hair and had beat him to a pulp.

_Stay away from my sister, you asshole!_

He'd shouted back, _You son of a bitch!_

And that was when the kicking and hitting and punching started.

Once, when passing the big kids classrooms on his way to the bathroom, he'd overheard a fifth grader shouting the same _son of a bitch _phrase. The kid had immediately been scolded by a teacher and sentenced to five detentions. Jace didn't know what it meant, but he knew it sounded good.

Now, with the scrapes and bruises, he wasn't so sure. He banged the door open, not caring if he carried dirt into the house, and stamped across the living room with his shoes still on.

His eight-year-old sister, Isabelle, screamed. "Jace! You're ruining our park!"

He looked down and saw himself surrounded by crudely cut green paper with what looked like flowers scattered around him. Of course, half of it was now brown mud. "Sorry," he muttered, not sorry at all. It was pathetic, this pretend-playhouse thing that girls her age did. He glanced back up, feeling a tiny spark of remorse when seeing Isabelle's crushed face. Another girl sat next to her, frowning.

He shrugged, continuing his way to the stairs. Footsteps pitter-platted after him. Ugh. "Look, Izzy," he growled, turning. And stopped.

"Are you okay?" The girl-whose-name-he-did-not-know stood next to him. She pointed at his bloody knees. "Did you get hurt or something?"

Jace cocked his head and took a good look at her. Her eyes were a deep shade of green, brilliant and sparkling, framed by copper eyelashes. She wasn't pretty, like Celine. In fact, she was only average. And her hair…there was just so much red everywhere. Her curls were fire-red, uncombed, and flying everywhere.

"Or something," he said, smirking a little. He knew from the slight widening of her eyes that he had ensnared her right then and there.

"Well," she said, swallowing. "Let's get you cleaned up. I'm Clary, by the way."

"Jace," he said, following her to the bathroom. He complied with her "playhouse game," pretending to be a patient while she played doctor. Isabelle, meanwhile, looked pissed.

Clary wasn't Celine – not as pretty, younger, and his little sister's best friend – but at least he got his knees cleaned up.

**Middle School**

Jace laughed as he sauntered into his seventh period classroom. Middle school was so much more different than elementary schools. And so much cooler. They had periods – well, he thought, snickering, not the _girl_ type. The class type, where each day had seven separate classes taught by different teachers. He was practically in high school already.

Suddenly, half of the girls at school looked _hot_. Kaelie, Aline, Seelie, Celine, Maia…it was like they had all grown boobs overnight, and their eyes and lips had been amplified ten times. Unnatural cake-plastered faces with makeup, of course, but it was worth it.

And he had practically morphed into a superstar himself. Jace knew he was good-looking, but it wasn't until the older eighth-graders started hitting on him that he realized exactly how hot he was. Like god hot.

When the bell rang, he hung around school for a little while longer with the cool kids, finally arriving home at four. He threw his backpack down and walked into the kitchen, where he knew Clary waited. She held out a peanut butter and jelly sandwich to him, beaming.

"How was school?"

She was always here, in his house. Since her parents had divorced a few years back, Clary had practically moved in with them, because of the tension and rivalry between her parents as they fought for complete control of their daughter.

"Fine." He said, walking away. Then at the last second, he tossed a brilliant smile back, thanking her for the snack, and her face brightened like a million light bulbs. She flounced off to Isabelle.

It wasn't like he disliked her or anything. In fact, he did – just not in the _like like_ way. She was just there, all the time, in the back. When he was younger, she was the one who had always taken care of his scrapes and cuts, encouraging him to continue riding his bike after he fell off, crying when he broke his arm, and now, making him snacks at times when he was hungriest.

But, compared to the middle school girls, well, she couldn't match at all. Elementary school kids suddenly seemed like babies to him. They had the same teacher all day. They still had recess, for heaven's sake. That was tantamount to naptime.

Basically, Clary was just his younger sister's best friend. That was all.

**High School**

He wasn't quite sure when things began changing. But one Saturday during his Junior year, while his friends were fooling around in the pool out back, he noticed a difference in her.

Jace had been in the water for a while now, laughing and flirting shamelessly with Kaelie while his girlfriend, Aline, sat bitch-glaring at them in the water. He couldn't help it. Flirting was like a second nature to him, and with Kaelie in a skimpy, red bathing suit…

Sure, Aline was pretty hot too, lying on a chair tanning. Sebastian sat on one side of her, smiling, leaning in so close that he was practically on top of her. Not that Jace cared. It was about time to dump her anyway, and move on. Maybe to Seelie? She was burning up the place with her long legs and that swimming suit which covered even less skin than Kaelie's.

"Hey," he said, extricating himself from Kaelie's grip. "I'm gonna get a soda. Be right back."

"Get me one too!" Jonathan hollered.

Dripping, he walked to the kitchen, where Clary stood before the fridge, eyes narrowed as she contemplated on what to eat.

"Hey," he said.

"Hey yourself," she replied. "What do you think sounds better: mint chocolate chip or – oh, Jesus Christ, Jace." She sighed dramatically as she took in the huge puddle gathering at his feet. "Couldn't you have dried off a bit before coming in and peeing all over the floor?"

He grinned. She was a Sophomore now, but still short, and while her hair was still red and unruly, she'd managed to comb it into two low, cute pigtails.

"Are you kidding? Girls dig this."

She scoffed. "You mean those sluts in the pool? Seriously, how many girls are you going to go through this year? Eleven?"

"Careful," he smiled. "If I didn't know you, I'd say you were jealous."

He knew perfectly well that she was.

As expected, Clary flushed and rolled her eyes in an attempt to cover the blush.

"Can you grab me a diet Pepsi?" He asked.

She reached into the refrigerator and grabbed a regular Pepsi, sticking her hand out towards him.

"I said _diet_ Pepsi, not regular, fattening Pepsi. I have to keep up this scorchingly-sexy shape if I want to be the star captain on the track team again."

She smirked. "Sorry. I drank the last of those yesterday."

Groaning, he took the can, and their fingers brushed. A spark of electricity flashed through his hand, nearly making him drop the can. He looked up, shocked, and their gazes locked.

What the hell had just happened?

"Are you okay, Jace?" Clary frowned, peering up at him. He was a full head taller.

"Uh, yeah. Yeah." He shook his head slightly to clear his head. She had been looking at him in the exact way she'd been looking at him for the last seven years. She hadn't felt anything different.

Jace shuffled out of the room, forgetting Jonathan's soda. His fingers still burned with heat and he rubbed them together, confused. Clary hadn't even been dressed in remotely revealing clothing, so what the hell had caused the spark?

Friction from the counter, he thought. Yes, that was it. Purely science.

…

"Mmmm," his mother said as the waiter cut huge chunks of cake and placed them on plates. His family and Clary were at some expensive restaurant, celebrating Isabelle's sixteenth birthday. "This looks delicious."

"It is," the waiter said. "It's our best."

"Well," his father said as the food was distributed. "Eat up."

The cake was indeed delicious. In fact, it was heaven. Jace was so absorbed in eating that he didn't bother talking. Bits of the conversation reached him. Isabelle's driver's license. The school play. Vampire Diaries and some hot badassed Damon dude.

He finished the cake in a few minutes and looked up, reaching for another slice.

Clary laughed. "Oh dear, Jace. You're gonna need to starve yourself for the next two weeks to burn off all this fat. Or else maybe Coach Herondale will kick you off the track team."

Whatever witty quip he had prepared died when he turned to look at her. She had just taken a forkful of chocolate cake in her mouth and his eyes practically bugged out of his head as she pulled the fork away from her lips. They were pink and perfect, with little chocolate crumbs on one side. Suddenly he wanted to kiss them away.

Water. Where the hell was the water?

He grabbed his cup and in his haste, choked on an ice cube.

Since when had he had thoughts like those around _Clary_? His sister's best friend whom he had known since third grade?

Taking a deep breath, Jace chanced another glance. She sat there, laughing, Clary-like. Just how he had always seen her as.

Good.

But then he noticed her eyes and how green they were. They were a beautiful, deep emerald color – the prettiest eyes he had ever seen. Her hair cascaded like a waterfall down her back, fiery red with bits of gold. The dress she wore wasn't fancy or anything, but the light pink shade brought out how fine her porcelain skin was and that made him notice how cute the light spray of freckles across her nose was.

She was pretty.

Jace gazed at her, mesmerized. She hadn't been pretty before, and now suddenly, she was. How had he been around her for so long and been so blind?

_I suppose that's what puberty does to people._

"Oh," she said, and he watched her lips. "I nearly forgot. Jace, your friend Sebastian? He's so nice."

"What?" He choked on some spit and coughed. Sebastian and Clary?

"Yeah, Sebastian," Isabelle answered. "He came over a few times when you were out and hung out for a while. I think he likes Clary."

_The hell?_

Jace turned to her, knowing his eyes were wide. "He likes you?"

"Yes, Jace," she smirked at his expression. "Guys are attracted to me, believe it or not. He asked me out on a date."

A date? With Sebastian? His asshole friend who flirted more often than he did?

"Oh, don't look so shocked." Clary's lips turned down slightly. "I'm not _that_ repulsive, am I?"

"No. NO," Jace said quickly. His mind was still reeling. "In fact, I'm pretty sure lots of guys are interested in you."

She shook her head, grinning, and turned back to Isabelle to discuss her future date.

Jace looked down at his plate. Suddenly, he wasn't so hungry anymore.

…

The date came and went. He managed to squeeze every last detail from her.

The movie: _Hope Springs_ – "Seriously? You went to watch something about _old people_? Is that supposed to be, like, romantic or something?"

It was a romantic comedy. And it'd been funny. And they'd laughed together.

Shit.

The dinner: Hooters – "Are you kidding me? That place is basically a bar. He took you to a bar."

It had been All-You-Can-Eat-Chicken-Wings Tuesday. Her favorite meal.

Fuck.

The ride home: a kiss and a second date.

He met this with silence, shook his head, and walked out of the room.

…

"Hey." Clary knocked on his door, and he glanced up from the mirror, where he was fixing his tie. "So, how do I look?"

She did a little spin for him, and he couldn't stop staring. She was beautiful. She was stunning. She was…Sebastian's date to Junior Prom.

"Awesome," he said, forcing a smile. "You look great."

"Thanks!" She beamed and walked over, fixing his tie. Her deft fingers quickly undid the knot he'd accidentally created. "Seriously, who would have known a guy like you couldn't tie a tie?"

It was so hard to breathe. She was standing so close, her fingers gently brushing his skin. "Well, I never really had to. You know, all my other dates did this for me." Shit. He sounded breathy.

She glanced up at him, eyes dark. "Oh. Sorry. I'll let Kaelie do this then."

"No, don't." He grabbed her hand. Sparks shot up his arm. "I want you to do it."

Smiling, she stepped closer, and it was over all too soon.

The doorbell rang. Sebastian.

Clary smiled nervously up at Jace, and then flounced downstairs to open the door. The look on Sebastian's face said everything Jace wanted to say, but couldn't. He looked at them, his friend with his jet black hair and Clary in her beautiful emerald dress, and felt something within him tighten.

He tried to convince himself that it was only because he was feeling protective of Clary, his sister's best friend. They had known each other for so long that he had a right to feel protective of her, like she was his own sister.

But it didn't feel that way at all.

In fact, it felt a lot like agony and misery.

…

Jace was dancing with Kaelie, but he wasn't. Well, he was physically holding Kaelie in his arms, but his mind was instead with Clary. She was standing by the punch, laughing about something with Sebastian, her eyes bright and shining. Going to Prom as a Sophomore was a pretty big deal for her. Isabelle was on the dance floor somewhere. He hadn't been surprised that she'd been asked. Guys were always chasing after Isabelle anyway.

But Clary. And Sebastian.

He still couldn't get over the bizarre scenario.

The song ended, and he headed straight for the punch. Clary had disappeared somewhere with Sebastian.

The same clenching he'd experienced earlier at home returned.

"Are you looking for that redhead?" Kaelie rolled her eyes.

He painfully dragged his gaze away from searching the crowd to look at her. "What?"

"Did you really think I didn't know? You were practically craning your head back to look at her when we turned around while dancing," she snarled.

"Uh…"

"Seriously?" She exclaimed when he didn't deny it. "You have me. _Me._ And instead you drool over her? Are you shitting me? I'm a thousand times hotter than she is. Take a good look at her, Jace. She's skin and bones. She's puny. She has no ass, no cleavage, and all that red hair. And that dress on her? It's pathetic. It's like she wants to look hot, but she's not pulling it off. I can't believe this." She laughed bitterly.

Even though he was fuming, Jace plastered on his devil-may-care look and cocked his head to one side, examining Kaelie. She perked up, jutting out her chest. Sure, Kaelie was hot. But Clary was beautiful. And Kaelie was a bitch. He chuckled.

"You know what?" He mused slowly. "I think you're getting quite boring."

Kaelie's mouth dropped open. "Excuse me?"

"You heard me. I'm done with you."

"What?" In her frightened and panicked state, she looked hilarious. "You can't do that. We're at _Prom._"

"Well, I just did."

It was weird. He didn't even feel bad about dumping her in the middle of the most anticipated dance ever. Normally he'd feel even a twinge of remorse – and really, he wasn't _that _much of an asshole, no matter how hard he tried to be. He turned and saw Clary.

She stood a few feet away, eyes wide and sparkling. His heart leaped involuntarily.

But then he realized they were tears.

"You're such an asshole," she whispered.

_For what? Breaking up with Kaelie?_

"Oh shit. That's why."

She had heard the whole thing. He hadn't defended her against everything Kaelie said. And he'd laughed – although that part was misconstrued. He could see it from her view, and shit, did he look like an asshole.

And as she walked away from him towards Sebastian, he felt what Kaelie felt – the whole world crashing down around him.

…

Jace scoured the whole house until he finally found her, curled in the loveseat in the library, reading. He leaned against the doorframe and studied her. The sunlight shone in through the window and set her hair into brilliant red flames that fell around her face, beautiful and serene.

"Hey."

She looked up, saw it was him, and her expression darkened. Pain and hurt flitted quickly across her features before she settled on annoyance.

Ouch. In all these years he'd known her, she'd never looked hurt by him before.

"What do you want now?"

He strode over and plopped down on an adjacent sofa. Somehow, he didn't think she'd appreciate sharing the loveseat. "I'm waiting for your Breakup Lecture."

Since she started middle school, Clary had given him a _You are such an asshole for breaking another girl's heart, Jace Wayland_ lecture after each girl he broke up with. Sometime during last year, though, she had stopped for some reason.

Clary returned to her book as if it was the most interesting thing in the world. "I thought you said those were pathetic and wasted your time."

Shit. Was that why she had stopped?

"I think I may have become a major asshole, so I thought a lecture might help get me back on track of just being a regular asshole."

She laughed sarcastically. "Don't know if it would do any good anyway."

He swallowed. That hurt.

"You looked great yesterday, you know. The dress was gorgeous."

"Thanks for the praise I never asked for," she said. "I'm returning the dress with Izzy in a few minutes."

"What? Why? You rocked it."

She sniffed. "Oh, really? It didn't look that way yesterday."

He took a deep breath. "Look, what you saw yesterday – "

"You don't have to explain, Jace. I really am pathetic. Chasing after you for all these years, hoping you'd like me back...I was stupid." Clary closed her book, prepared to leave. "I'm fine with being friends anyway. It was just surprising to hear you laugh at me, that's all."

Jace jumped up before she could stand. "That's it. That's exactly what I wanted to talk about. I didn't laugh at you. I was laughing at how pathetic Kaelie seemed." At the dubious look on her face, he groaned and ran his fingers through his hair.

"Look, Clary. I know I haven't been the nicest guy in the world to you, and I know I've always just taken you for granted. You've always been here for me, and I – well, honestly? Sometimes I kinda treated you like shit. But I know you. Better than any other guy out there. We've known each other for seven years already. You're Isabelle's best friend. And when you went out with someone like Sebastian, I just, uh, I, uh – I'm – I –"

Since when had he stumbled for words?

It didn't help when Clary looked up at him, a small smirk forming on her lips. "You what?"

"I felt like, like, uh, really, uhm – oh, fuck this." He leaned forward and kissed her.

It wasn't a movie-like, epic love kiss. His hand slammed ungracefully against the loveseat, and he was bent over, leaning down, but he forgot all of that as he was consumed by the kiss. For once he didn't think about anything – kissing techniques, how to get to the next level – and just kissed her. She was sweet and warm, and when her hands fisted in his shirt, pulling him down against her, he nearly lost his mind, groaning softly.

"C-Clary?"

They broke apart reluctantly. Isabelle stood at the door, her mouth hanging slack.

"What the hell?" She snapped. "Jace, I want to talk to you. Right now. Outside. And Clary? Don't even think about trying to escape. You're next."

He grinned, planting a quick kiss on Clary's swollen lips before squaring his shoulders to endure Isabelle's version of a lecture, which had to be ten-thousand times more severe than Clary's Breakup Lectures. With a lot more swearing, no doubt.

Not that it mattered. Nothing mattered, except that his sister's best friend was now his girlfriend.

**Thoughts? Like? Dislike? What do you think about Jace's growing up? **

**His thoughts when he was young were pretty innocent…well, except for the swearing, but seriously, kids nowadays swear like hell. From a hella young age. **

**And then middle school, when he's going through puberty and all his thoughts are perverted hahahaha. Because a lot of kids, if they weren't already corrupted, become corrupt and perverted in middle school. At least I did, but I'm a girl so…idk, maybe guys are worse. **

**And then high school! When he finally grows up a bit(:**

**This is a oneshot, by the way.**

**And yes, that was a Vampire Diaries reference in there. Ian Somerhalder is hothothot. And maybe im on a vampire craze or something, but ive also recently started Vampire Academy/Bloodlines. **

**Adrian Ivashkov…ahhh, I love him(: Can't wait until The Indigo Spell comes out! And then a month later Clockwork Princess comes out too! Yaay! **

**And now…back to working on The Kissing Dilemma.**

**This took a while to write, so please review!**


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